Collators having pockets which move relative to a sheet withdrawing or ejecting station have been widely used. One type of collator, shown in Mestre U.S. Pat. No. 2,940,750, uses clamping mechanisms on a conveyor to withdraw and transport sheets from sheet receiving pockets. This collator has a collating speed on the order of 25,000 sheets per hour.
Another collator, shown in Blowsky U.S. Pat. No. 3,540,721, is provided with feed rolls in sheet receiving pockets, formed in a drum, to eject the sheets from the pockets and has a collator speed of about 28,000 sheets per hour.
The sheet withdrawing mechanism of the invention is applicable to any form of collator having pockets, such as formed by spaced shelves or partitions, in which the pockets move past a sheet withdrawing or ejecting station. A plurality of the pockets are loaded with piles of sheets, the sheets in each pocket being the same and successive pockets being loaded with piles of sheets of different pages to complete a book. The sheet withdrawing mechanism uses spider means including at least one spider having a body and preferably a plurality of arms each carrying a friction member, which rotates in timed sequence to the movement of the pockets relative to the sheet withdrawing station so that each arm sweeps into and out of a pocket in succession. With the speed of the friction member greater than that of the pockets the friction member on the end of each arm engages the top sheet in the pile and at least partially withdraws it from the pocket. Adjacent secondary sheet withdrawing means may be provided to complete the withdrawal of the sheet from the pocket and deposit it in a pile on a deposit table.
An object of the invention is to construct a simple sheet withdrawing mechanism having at least one and preferably a plurality of outwardly extending resiliently biased arms which rotate and sequentially reach into pockets formed by movable and relatively closely spaced partitions. Sheets in the pockets are engaged by arms and withdrawn at least far enough to be received by adjacent secondary sheet withdrawing means which completes the withdrawal of the sheets from the pockets.
Another object is to construct a sheet withdrawing mechanism having outwardly extending arms with a rotating withdrawing roll on the end of each arm. Rotation of the roll adds to the sweep of the arm in at least partially withdrawing a sheet so that the partitions forming the pockets may be relatively closely spaced with the pockets of relatively small vertical dimensions, thereby enabling a larger number of pockets to be provided in a given overall dimension.
A further object is to construct sheet withdrawing mechanisms of the types described in combination with advancing means for the spider arms so that as the pile of sheets is reduced in height, the phase of the spider arm is advanced with respect to the phase of the pockets to accommodate for the reduction in height of the piles of sheets.
Another object is to construct a sheet withdrawing mechanism having a rotary spider which combines the structures of spider advancing means and a rotating withdrawing roll carried by the end of each arm of the spider.
A further object is to construct a combination of a collator having moving pockets with the sheet withdrawing mechanism for at least partially withdrawing a sheet from the top of a pile of sheets in each of a plurality of the pockets at a sheet withdrawing station, which mechanism utilizes a rotating spider preferably having a plurality of radially extending, resiliently biased arms. The spider rotates in timed sequence with the movement of the pockets so that each arm, in its rotation, enters its respective pockets and engages the top sheet of the pile of sheets therein to withdraw the top sheet from the pile sufficiently far to be received by adjacent secondary withdrawal means which completes the withdrawal of the sheet from each pocket.